- 3738 - MARS - and its satellite Phobos? Up until now, 2022, Mars has been generally considered a geologically dead planet. However, new reports that seismic signals indicate vulcanism still plays an active role in shaping the Martian surface.
--------------------- 3738 - MARS - and its satellite Phobos?
- Since 2018, when the NASA InSight Mission deployed the SEIS seismometer on the surface of Mars, seismologists and geophysicists have been listening to the seismic pings of more than 1,300 marsquakes. Again and again, the researchers registered smaller and larger Mars quakes.
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- A detailed analysis of the quakes’ location and spectral character brought a surprise. With epicentres originating in a region consisting of a series of “rifts’ or ‘graben‘, these quakes tell a new story. A story that suggests vulcanism still plays an active role in shaping the Martian surface.
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- Researchers analyzed a cluster of more than 20 recent marsquakes that originated in the “Cerberus Fossae graben” system. From the seismic data, scientists concluded that the low-frequency quakes indicate a potentially warm source that could be explained by present day molten lava, magma at that depth, and volcanic activity on Mars.
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- When they scanned observational orbital images of the same area, they noticed that the epicentres were located very close to a structure that has previously been described as a “young volcanic fissure.” Darker deposits of dust around this fissure are present not only in the dominant direction of the wind, but in all directions surrounding the Cerberus Fossae Mantling Unit.
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- The darker shade of the dust signifies geological evidence of more recent volcanic activity. perhaps within the past 50,000 years, relatively young, in geological terms.
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- Exploring Earth’s planetary neighbors is no easy task. Mars is the only planet, other than Earth, in which scientists have ground-based rovers, landers, and now even drones that transmit data. All other planetary exploration, so far, has relied on orbital imagery.
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- InSight’s SEIS is the most sensitive seismometer ever installed on another planet. It affords geophysicists and seismologists an opportunity to work with current data showing what is happening on Mars today, both at the surface and in its interior.
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- Mars is important for understanding similar geological processes on Earth. The red planet is the only one we know of, so far, that has a core composition of iron, nickel, and sulphur that might have once supported a magnetic field.
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- Topographical evidence also indicates that Mars once held vast expanses of water and possibly a denser atmosphere. Scientists have learned that frozen water, although possibly mostly dry ice, still exists on its polar caps.
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- Looking at images of the vast dry, dusty Martian landscape it is difficult to imagine that about 3.6 billion years ago Mars was very much alive, at least in a geophysical sense. It spewed volcanic debris for a long enough time to give rise to Tharsis Montes region, the largest volcanic system in our solar system and the Olympus Mons, a volcano nearly three times the elevation of Mount Everest.
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- The quakes coming from the nearby Cerberus Fossae suggest that Mars is not quite dead yet. Here the weight of the volcanic region is sinking and forming parallel graben ,or rifts, that pull the crust of Mars apart, much like the cracks that appear on the top. What astronomer are seeing are the last remnants of this once active volcanic region or that the magma is right now moving eastward to the next location of eruption.
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- Astronomers are also interested in the martian moon, “Phobos“. Europe's Mars Express spacecraft has peered deeper into the subsurface of the Martian moon than ever before, finding hints of unknown structures that could be clues as to the moon's origin.
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- “Mars Express“ is a 19-year-veteran spacecraft in orbit around Mars. It came within 51.6 miles of Phobos on September 22, 2022 and was able to probe beneath the moon's surface using upgraded software on its MARSIS instrument (Mars Advanced Radar for Subsurface and Ionosphere Sounding).
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- Understanding the interior structure of Phobos could be key in solving the mystery of its origin. Mars has two moons, Phobos and Deimos, namedafter the gods of 'fear' and 'panic' in Greek mythology. Unlike the major moons of our solar system, Phobos and Deimos are tiny, just 16.7 miles across and 9.3 miles across.
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- They have a similar composition to carbonaceous C-type asteroids, and are irregularly shaped like asteroids, which has led to the suspicion that they actually are rogue asteroids captured by Mars' gravity. However, both Phobos and Deimos' orbits around the red planet are over Mars' equator and both orbits are extremely circular, which suggests they formed around Mars. If they had been captured, they would be expected to have more elliptical orbits in different planes.
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- MARSIS involves a 40-meter-long antenna beaming low frequency radio waves down to the surface. Most of the radio waves are reflected directly back from the surface, but some penetrate deeper, where they encounter transitions between layers of different composition and structure, and are reflected back by these boundaries. The stronger the reflection in the resulting 'radargram', the brighter the returning radio signal.
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- A 'radargram' acquired by MARSIS during the flyby of Phobos in September, 2022. revealed the ‘echoes’ created when the radio signal emitted by MARSIS bounces off something and returns to the instrument.
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- MARSIS had been designed to probe Mars' interior from an orbital distance of more than 155 miles, but the recent software upgrade allows MARSIS to operate at much closer distances, permitting its use during close fly-bys of the moons.
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- Getting even closer to Phobos provided radargrams with even greater resolution. The plan over the next few years is to employ MARSIS as close as 24.9 miles.
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- The orbit of Mars Express has been fine-tuned to get us as close to Phobos as possible during a handful of flybys between 2023 and 2025. Mars Express isn't the only mission focused on Phobos. In September, 2024, the Japanese Aerospace Exploration Agency (JAXA) plans to launch the Martian Moon eXploration (MMX) spacecraft.
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- Much like JAXA's Hayabusa2 mission to retrieve samples from the near-Earth asteroid Ryugu, MMX will capture at minimum 10 grams of regolith from Phobos' surface. MMX will also deploy a small rover onto the surface, before venturing off to take a good look at Mars' second moon, Deimos, and then returning to Earth with the precious Phobos samples that will be analyzed in scientists' laboratories here on Earth.
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- November 9, 2022 3738
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